1. Field of Invention
The present invention relates to a continuously variable valve lift/timing apparatus, and more particularly, to a continuously variable valve lift/timing apparatus capable of independently controlling a valve lift and valve timing in accordance with an operational state of an engine.
2. Description of Related Art
An internal combustion engine produces power by receiving fuel and air in a combustion chamber and combusting fuel and air.
When air is sucked, an intake valve is operated by an operation of a camshaft, and air is sucked into the combustion chamber while the intake valve is opened.
In addition, an exhaust valve is operated by an operation of the camshaft, and air is discharged from the combustion chamber while the exhaust valve is opened.
However, optimal operations of the intake valve and the exhaust valve are varied in accordance with a rotation speed of an engine.
A proper lift or proper valve opening and closing timing is varied in accordance with the rotation speed of the engine.
In order to implement a proper valve operation in accordance with the rotation speed of the engine, various researches have been conducted.
For example, a variable valve lift (VVL) apparatus or a continuously variable valve lift (CVVL) apparatus implemented so that the valve is operated with another lift in accordance with revolutions per minute of an engine, and a variable valve timing (VVT) apparatus which opens and closes the valve at proper timing in accordance with revolutions per minute of the engine have been researched.
FIG. 9 is a view for explaining lift variation of a general continuously variable valve lift/timing apparatus.
Referring to FIG. 9, in the general continuously variable valve lift apparatus, when a valve lift is varied, in accordance with a rise in a lift profile, the valve timing is advanced as illustrated in FIG. 9A, the valve timing is fixed as illustrated in FIG. 9B, or the valve timing is retarded, as illustrated in FIG. 9C.
The reason is that in the case of the general continuously variable valve lift apparatus, the timing according to the lift is determined by an initial design, and the same timing is always formed at the same lift in accordance with a mechanical configuration.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.